create a checkbox in the preferences of your app to toggle it on , unless you do that you have to use one of the methods above directly in code.

2 – since 1.0 sparkle implemented sparkle:shortVersionString to match CFBundleShortVersionString , the problem however is that it is only used when it also sees a different version in sparkle:version , for example if your app has

CFBundleVersion 1
CFBundleShortVersionString 1.1
and the appcast has sparkle:version=”1″
sparkle:shortVersionString=”1.2″sparkle will say you have the latest version , it only uses shortVersionString if version differs from CFBundleVersion

3 – some times you might also want to force a update , either when the user clicks a Update Now button or when the application launches

Both check for a update , however the first way also notifies the user if the current version is the latest one , so should only be triggered from a user action.

The second can be ran transparently on startup as it will not alert the user unless there is a new update , remember to set automaticallydownloadupdates off , or else the updates will only get downloaded and never installed (bug in Sparkle 1.5 b6)